A major expense of a rectification plant for the separation of a fluid mixture into components based on their relative volatility is the cost of the column casing and the space required for the column. This is particularly the case where two or more columns are required to conduct the separation. Such multi-column systems are often used in cryogenic rectification, such as in the cryogenic rectification of feed air, where columns may be stacked vertically or located side by side. It would be highly desirable to have a system which will enable rectification to be carried out with reduced column cost and with reduced space requirements for the columns.
Accordingly it is an object of this invention to provide a column system for rectification which has reduced costs and space requirements over comparable conventional systems.